The present invention relates to a carbon/insulator structure and, more particularly, to a thin, integrated carbon/insulator structure for a primary electrochemical cell. The invention also relates to a method for fabricating thin integrated carbon/insulator structures for primary electrochemical cells.
Primary electrochemical cells are utilized for a wide variety of applications and are commonly available in a large assortment of sizes and shapes. A common design of an electrochemical cell includes an electrochemical system comprising an anode, a porous carbon cathode structure separated from the anode by a porous separator, and an electrolytic solution in contact with the aforementioned cell components. In a preferred construction of a cell, the anode includes an oxidizable active alkali metal such as lithium, the carbon cathode structure includes an aggregation of porous carbon globules or conglomerates, the porous separator is of fiberglass, and the electrolytic solution is a cathodelectrolyte solution including a reducible soluble cathode such as thionyl chloride and an electrolyte solute such as lithium tetrachloroaluminate dissolved in the thionyl chloride.
In an electrochemical cell as described hereinabove, it is sometimes desirable to achieve a high discharge rate (greater than 1 mA/cm.sup.2) for a relatively short period of time. This result can ordinarily best be achieved by using thin electrodes, including the aforementioned porous carbon cathode structures. Thin porous carbon cathode structures have been produced by spraying or otherwise depositing a carbon slurry material onto a thin metallic substrate which is then processed (e.g., by drying and curing operations) to achieve a carbon thickness on the metallic substrate in a range of 0.001 to 0.005 inch. Electrodes produced in this fashion, however, are very fragile and difficult to handle. Further, in the case of electrodes having a carbon thickness in the upper end of the above-mentioned range, the carbon is susceptible to blistering and falling apart, thereby requiring relatively thick metallic substrates for support purposes. The metallic substrates are also required where the carbon thickness is to be controlled over a large surface area.